Construction methods for loess tunnels with super-large cross-section based on displacement control of surrounding rock

In order to determine the optimal construction method for loess tunnels with super-large cross-section, considering the elastoplastic constitutive relation between tunnel lining and soil and using FEM software ANSYS, a case of loess tunnel with super-large cross-section is calculated by means of six kinds of methods, which are CD method, CRD method, single-wall excavation method, double-wall excavation method, pre-excavation core soil method and pre-retaining core soil method. By comparing the displacement results of control nodes, the results show that, for the loess tunnel with super-large cross-section, the CRD method is the optimal one. When temporary support is added in construction, the central temporary support has great influence on the stability of surrounding rock, and equivalent plastic strain is increased by about 20% before and after demolition of the temporary support.